Vehicle control device operating safety device based on object position

ABSTRACT

A vehicle control device including an acquisition unit for acquiring an object position detected by an object detection sensor, an identification determination unit for determining that a plurality of object positions relates the same object when the plurality of object positions is acquired by the acquisition unit, and a selection unit that selects a current target position from among the plurality of object positions based on the previous object position that was set as the operation target of a safety device in the case when the identification determination unit determines that the plurality of object positions relates to the same object, and an operation control unit for controlling the operation of the safety device based on the current target position.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of priority fromearlier Japanese Patent Application No. 2017-8680 filed Jan. 20, 2017,the description of which is incorporated herein by reference.

BACKGROUND Technical Field

The present disclosure relates to a vehicle control device for operatinga safety device based on an object position.

Description of the Related Art

A pre-crash safety (PCS) control for mitigating or preventing collisiondamage between an own vehicle and objects (another vehicle, pedestrians,road structures and the like) located in front of the travelingdirection of the own vehicle has been realized. In the PCS control, forexample, a time to collision (TTC) which is the time until the ownvehicle collides with an object is obtained from the distance betweenthe own vehicle and the object and the relative speed, and a safetydevice such as an alert device and a brake device installed in the ownvehicle is operated based on TTC.

For example, JP-A 2010-9232 discloses a PCS control in a state in whicha plurality of objects are present in front of the own vehicle.Specifically, the vehicle control device of PTL 1 acquires a detectionpoint for each of a plurality of objects, and calculates a TTC for eachof the detection points. Moreover, the plurality of detection points areranked each time based on each TTC calculated, and at that time, thedetection point having the highest rank is selected as the operationtarget of the safety device, and whether the safety device is operatedis determined for the operation target.

There are cases in which a plurality of detection points are acquired bya radar and the like for the object even though the object deemed to bethe detection target in front of the own vehicle is actually one object.In such cases, it is considered that there are no large differencesbetween each TTC of these plurality of detection points. Therefore, inthe aforementioned vehicle control device, it is considered that theranking between the detection points on the same object changes for eachof the calculations of TTC. In such cases, there is the risk that theoperation target of the safety device will frequently switch, and theoperation of the safety device will become unstable.

SUMMARY

The present disclosure provides a vehicle control device which canappropriately select a detection point to be an operation target, andcan properly operate a safety device.

A vehicle control device of the present disclosure is constituted inorder for object detection sensors to detect the position of the objectpresent in front of the traveling direction of the own vehicle, andoperate a safety device for avoiding a collision of the own vehicle withan object or for mitigating the collision damage based on the detectionresult.

The vehicle control device of the present disclosure includes anacquisition unit that acquires an object position detected by the objectdetection sensor, an identification determination unit that determinesthat a plurality of object positions is on the same object when theplurality of object positions has been acquired by the acquisition unit,a selection unit that selects a current target position from among theplurality of object positions based on the previous object positionwhich has been set as the target position of the safety device tooperate, in the case where the identification determination unitdetermined that that the plurality of object positions is on the sameobject, and an operation control unit that controls the operation of thesafety device based on the current target position.

In object detection, a plurality of object positions on the same objectmay be acquired even though there is actually one object (the sameobject). In such cases, it is considered that the target position whichis the operation target of the safety device frequently switches, andthere is the risk that the operation of the safety device will becomeunstable.

With regards to this point, in the aforementioned configuration, when aplurality of object positions have been acquired, it is determined thatthe plurality of object positions is on the same object, and in the casewhen it was determined that the plurality of object positions is on thesame object, the current target position is selected from among theplurality of object positions based on the previous object positionwhich was set as the target position. In this case, by selecting thecurrent target position based on the previous object position which wasset as the target position, the current target position can be selectedwhile taking the switching of the target position into account.Therefore, even when a plurality of object positions on the same objecthave been acquired, it is possible to stably select the object positionwhich is the target position, and consequently, the safety device can beoperated properly.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a block diagram showing a schematic configuration of a vehiclecontrol device;

FIG. 2 is a diagram for explaining the object position acquired by apreliminary determination unit;

FIG. 3 is a diagram showing the case when a plurality of objectpositions is acquired for the same object;

FIG. 4 is a diagram showing the case when the object positions arerespectively acquired for a plurality of objects; and

FIG. 5 is a flowchart showing a process for selecting the targetposition.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a pre-crash safety system (hereinafter, referred to asPCSS) which is a vehicle control device. The PCSS is an example of avehicle system installed in a vehicle, and detects an object which ispresent around the own vehicle, and when there is a possibility of thedetected object colliding with the own vehicle, performs an operationfor avoiding the collision of the own vehicle with the object, or anoperation for mitigating the collision.

The own vehicle 50 shown in FIG. 1 comprises, a radar device 21 and animaging device 22 as the object detection sensors, various sensors suchas an accelerator sensor 23, a brake sensor 24, a steering sensor 25 anda speed sensor 26, an electronic control unit (ECU) 10, an alert device31, a brake device 32, and a steering device 33 as the safety device. Inthe embodiment shown in FIG. 1, the ECU 10 functions as the vehiclecontrol device.

The radar device 21 utilizes electromagnetic waves (survey waves) whichhave directivity such as a millimeter wave or a laser to detect theobject in front of the own vehicle, and is attached so that the opticalaxis in the front portion of the own vehicle 50 faces the front of theown vehicle. The radar device 21 uses a radar signal to scan an areawhich spreads in a predetermined range toward the front of the ownvehicle at predetermined intervals, and acquires the relative position(the object position), the relative speed and the like of each object asobject information by receiving the electromagnetic waves reflected bythe surface of the object in front of the own vehicle. When the ownvehicle 50 is the origin, the object position is acquired as therelative coordinates of the position with the vehicle width direction ofthe own vehicle 50 defined as the X axis, and the traveling direction ofthe own vehicle 50 defined as the Y axis. In the object position, thecomponent of the vehicle width direction (X axis) indicates thehorizontal position of the object relative to the own vehicle 50, and acomponent of the traveling direction (Y axis) of the own vehicle 50indicates the distance (the relative distance) from the front of theobject. Note that, the object information acquired for each object isinput into the ECU 10.

The imaging device 22 is an onboard camera, and is constituted using,for example, a charge-coupled device (CCD) camera, a complementarymetal-oxide-semiconductor (CMOS) image sensor, a near-infrared cameraand the like. The imaging device 22 is attached at a predeterminedheight (for example, near the top of the front windshield) in the centerof the vehicle width direction of the own vehicle 50, and captures, froma bird's eye view point, an area that spreads toward the front of theown vehicle over a predetermined angle range. The captured images areinput into the ECU 10 at each predetermined interval. Note that, theimaging device 22 may be a monocular camera, and may be a stereo camera.

In addition, an accelerator sensor 23 which detects the operation amountof the accelerator pedal, a brake sensor 24 which detects the operationamount of the brake pedal, a steering sensor 25 which detects thesteering angle of the steering wheel and a speed sensor 26 which detectsthe speed of the own vehicle 50 are provided in the own vehicle 50. Thedetection results by these various sensors are input into ECU 10.

The alert device 31 uses a control command from the ECU 10 to alert thedriver that an object is present in front of the own vehicle. The alertdevice 31 is constituted by, for example, a speaker provided in thepassenger compartment, and a display unit for displaying the image.

The brake device 32 is a brake device for stopping the own vehicle 50.The brake device 32 operates when the possibility of a collision withthe front of the object is high. Specifically, the braking force for thebraking operation by the driver is made stronger (brake assistfunction), and automatic braking is performed unless the brakingoperation is performed by the driver (automatic brake function).

The steering device 33 is a device which controls the cruising path ofthe own vehicle 50. The steering device 33 operates when the possibilityof a collision with the front of the object is high. Specifically, thesteering operation is supported by the driver (steering avoidancesupport function), and automatic steering is performed unless thesteering operation is performed by the driver (automatic steeringfunction).

The ECU 10 is configured as a well-known microcomputer provided with acentral processing unit (CPU) and various memory (ROM and RAM), andperforms control in the own vehicle 50 with reference to the calculationprogram and the control data in the memory. The ECU 10 detects theobject based on the object information input from the radar device 21and the captured images input from the imaging device 22, and based onthe detection result, a PCS which makes the alert device 31 as thesafety device, and the brake device 32 and the steering device 33 as thecontrol targets is performed.

As shown in FIG. 1, the ECU 10 comprises an object identification unit11, an operation state determination unit 12, a preliminarydetermination unit 13, a target selection unit 14, an operation timingcalculation unit 15, an operation determination unit 16 and a controlunit 17.

The object identification unit 11 inputs the object information of eachobject from the radar device 21. Specifically, the radar position LT asthe relative coordinates of the position, and the relative speed areidentified for each object.

The object identification unit 11 inputs the captured images from theimaging device 22, and identifies the image position CT based on thecaptured images. Specifically, the type of object which is present infront of the own vehicle is identified by comparing the input capturedimages with prepared dictionary information for object identification bypattern matching. The dictionary information for object identificationis separately prepared in accordance with the type of object, forexample, a bicycle, motorcycle, pedestrian and road obstacles, and isstored in the memory. Moreover, the object identification unit 11identifies the coordinate of the Y axis based on the vertical positionof the object in the captured images, and identifies the coordinate ofthe X axis based on the horizontal position of the object in thecaptured images.

Further, based on the input of the radar device 21, and the imageposition CT based on the input of the imaging device 22, the objectidentification unit 11 associates the objects located in the vicinity ofeach other as objects based on the same object based on the radarposition LT. Namely, the radar position LT is fused with the imageposition CT to produce a fusion position FT. Specifically, in the casewhen the radar search area which is set based on the radar position LTand the area overlaps with the image search area which is set based onthe image position CT are present, the fusion position FT is produced.In this case, for example, the X coordinate of the fusion position FT isset as the X coordinate of the image position CT, and the Y coordinateof the fusion position FT is set as the Y coordinate of the radarposition LT.

On the one hand, when the fusion position FT is not produced, forexample, when the aforementioned radar search area does not overlap withthe aforementioned image search area, the radar position LT and theimage position CT are respectively identified. The identified objectposition is input in the preliminary determination unit 13.

The preliminary determination unit 13 determines whether or not there isa possibility that the own vehicle 50 will collide with each objectposition input from the object identification unit 11. Specifically, thepreliminary determination unit 13 sets a collision prediction area S inwhich the object is set as the operation target of the safety device.The collision prediction area S is set as an area partitioned by, forexample, as shown in FIG. 2, a right regulation value XR and a leftregulation value XL which are set as the regulation values of thevehicle width direction (X axis), and a depth L which is set as theregulation value of the traveling direction of the own vehicle 50. Notethat, the right regulation value XR and the left regulation value XL maybe changed in accordance with the type of object and the like.

Moreover, the preliminary determination unit 13 determines whether ornot each object position input from the object identification unit 11belongs in the collision prediction area S. When the object positionbelongs in the collision prediction area S, it is determined that thereis a possibility that the own vehicle 50 will collide with an objectposition and the object position is acquired.

For example, in FIG. 2, a plurality of object positions (detectionpoints) T1 to T5 in front of the own vehicle 50 are identified by theobject identification unit 11, and among these object positions T1 toT5, the preliminary determination unit 13 determines that the objectpositions T1 to T3 belong in the collision prediction area S, and theobject positions T1 to T3 are acquired. The acquired object positions T1to T3 are input to the target selection unit 14. Note that, the objectpositions T1 to T5 of FIG. 2 indicate either the radar position LT, theimage position CT or the fusion position FT. Note that, in the presentembodiment, the object identification unit 11 and the preliminarydetermination unit 13 correspond to the “acquisition unit”.

The target selection unit 14 selects a target position Tt to be theoperation target of the safety device from among the object positionsinput from the preliminary determination unit 13. Specifically, thetarget position Tt is selected based on the object informationpertaining to each object position which is input. Note that this willbe explained in detail below.

The operation timing calculation unit 15 sets the operation timing foroperating a safety device such as an alert device 31. When the operationtiming is set, the determination result of the operation statedetermination unit 12 and the vehicle speed detected by the speed sensor26 are added.

The operation state determination unit 12 determines whether or not thecollision avoidance operation has been started by the driver in order toavoid a collision between the front of the object and the own vehicle50. In the present embodiment, determination conditions relating to thedriver's accelerator operation, brake operation and steering operationare included. For example, it is determined based on the steering angledetected by the steering sensor 25 that the collision avoidanceoperation has been started by the driver.

For example, when it was determined by the operation state determinationunit 12 that the collision avoidance operation has been performed by thedriver, the operation timing calculation unit 15 performs a processwhich delays the operation timing by making the value of the operationtiming smaller than the operation timing of the reference.

The operation determination unit 16 determines whether or not to operatethe safety device based on the time to collision (TTC) which is the timeuntil the own vehicle 50 collides with the target position Tt selectedby the target selection unit 14. Specifically, it is determined whetheror not the TTC is less than the operation timing set by the operationtiming calculation unit 15, and when the TTC is less than the operationtiming, an operation signal indicating that the safety device is to beoperated is output to the control unit 17.

The control unit 17 transmits a control command to the alert device 31,the brake device 32 and the steering device 33 when the operation signaloutput from the operation determination unit 16 is input. The safetydevice is operated based on the control command, and, for example, analert to the driver is performed by the alert device 31, the brakecontrol is performed by the brake device 32 and steering control isperformed by the steering device 33. Note that, in the presentembodiment, the operation determination unit 16 and the control unit 17correspond to the “operation control unit”.

There are cases a plurality of object positions are acquired regardlessof whether the object that is to be detected in front of the vehicle 50is actually one object. FIG. 3 shows the case when a bicycle 60 ispresent in front of the own vehicle 50, and object positions P1 and P2on the bicycle 60 are acquired by the preliminary determination unit 13.In short, in this case, two (plural) object positions are acquiredregardless of whether the bicycle 60 is the same object. Note that, thearrow in FIG. 3 indicates the movement direction of the bicycle 60, andin this case, the bicycle 60 is crossing from the left side of thetraveling direction of the own vehicle 50 toward the right side of thetraveling direction.

In this case, in the conventional vehicle control device, the targetposition Tt is selected based on the TTC from among the plurality ofobject positions. Specifically, the target selection unit 14 calculatesthe TTC for each object position input from the preliminarydetermination unit 13, and the object position having the smallest TTCamong the calculated TTC is selected as the target position Tt.

Referring to FIG. 3, both the object positions P1 and P2 are objectpositions pertaining to the bicycle 60, thus, it is considered that therelative distance to an object position T1 and the relative speed aresubstantially equal to the relative distance to the object position T2and the relative speed. In short, in this case, the TTC pertaining tothe object position T1 and the TTC pertaining to an object position T2are substantially equal. Therefore, the magnitude of the TTC between theobject positions P1 and P2 can be changed each time the TTC iscalculated by the detection error and the like when calculating the TTC.As a result, there is the risk that the target position Tt which isselected in the target selection unit 14 will frequently switch, and theoperation of the safety device will become unstable.

In the present embodiment, when the plurality of object positions isacquired, it is determined that the plurality of object positions is onthe same object. Moreover, in the case when it was determined that theplurality of object positions is on the same object, the current targetposition Tt is selected from among the plurality of object positionsbased on the previous object position set as the target position Tt. Inshort, when the plurality of object positions is acquired on the sameobject, the target position Tt can be stably selected by selecting thecurrent target position Tt based on the previous target position Tt.

In the present embodiment, the target selection unit 14 comprises anidentification determination unit 141, a selection unit 142, areliability calculation unit 143, a first calculation unit 144 and asecond calculation unit 145.

The identification determination unit 141 inputs the object positionacquired by the preliminary determination unit 13. Namely, the objectposition belonging to the collision prediction area S among the objectpositions identified by the object identification unit 11 is input inthe identification determination unit 141.

Further, the identification determination unit 141 determines that theplurality of object positions are on the same object when a plurality ofobject positions was input. Specifically, it is determined that theplurality of object positions is on the same object based on thedistance (relative distance) to the own vehicle 50 of each objectposition, the relative speed, and the horizontal position in thedirection orthogonal to the traveling direction of the own vehicle 50.In more detail, when all of the difference between the relative distancein one object position and the relative distance in the other objectposition is within a predetermined range, the difference between therelative speed in one object position and the relative speed in theother object position is within a predetermined range, and thedifference between the horizontal position in one object position andthe horizontal position in the other object position is within apredetermined range are satisfied, it is determined that the pluralityof object positions is on the same object. Therefore, for example, it isdetermined that the object positions P1 and P2 pertaining to the bicycle60 in FIG. 3 are on the same object.

Note that, as the same determination as stated above, when any one ortwo of the difference between the relative distance in one objectposition and the relative distance in the other object position iswithin a predetermined range, the difference between the relative speedin one object position and the relative speed in the other objectposition is within a predetermined range, and, the difference betweenthe horizontal position in one object position and the horizontalposition in the other object position is within a predetermined rangeare satisfied, it may be determined that the plurality of objectpositions is on the same object.

The selection unit 142 repeatedly selects the current target position Ttwithin a predetermined period based on the determination result of theidentification determination unit 141. The selection unit 142preferentially selects the object position as the current targetposition Tt when it was determined that the plurality of objectpositions is on the same object by the identification determination unit141, and, when the object position is present as the previous targetposition Tt among the plurality of object positions.

On the one hand, the selection unit 142 selects the object positionhaving a higher reliability which was calculated in the reliabilitycalculation unit 143 from among the plurality of object positions whenit was determined that the plurality of object positions is on the sameobject by the identification determination unit 141, and, when theobject position set as the previous target position Tt is not presentamong the plurality of object positions, and, for example, when theplurality of object positions is acquired in the object which wasdetected for the first time.

The reliability calculation unit 143 calculates the reliability in thecase when the identification determination unit 141 determined that theplurality of object positions is on the same object. The reliability isan index indicating the reliability (probability) of the positioninformation of the object position, and means that if the reliability ishigh, the position accuracy of the object position is high, and meansthat if the reliability is low, the position accuracy of the objectposition is low. Various methods can be used when calculating thereliability, and in the present embodiment, the reliability iscalculated by the presence of fusion. Namely, when the object positionis a fusion position FT, the reliability calculation unit 143 calculatesthe reliability so as to be higher compared to when there is no thefusion position FT (in the case of the radar position LT or the imageposition CT).

As described using FIG. 3, for example if the previous target positionTt is the object position P2 among the object positions P1 and P2pertaining to the bicycle 60, the selection unit 142 selects the objectposition P2 as the current target position Tt. Therefore, when thepreliminary determination unit 13 acquires the object positions P1 andP2 on the bicycle 60, the object position P2 is continuously selected asthe target position Tt. On the one hand, when the object positions P1and P2 are acquired for the first time, either the object position P1 orP2 is selected based on the reliability. For example, if the objectposition P2 is the fusion position FT and the object position P1 is theradar position LT, the object position P2 in which the reliability is apredetermined value or greater is selected.

There are cases where there actually are a plurality of objects deemedto be the detection targets present in front of the own vehicle 50. InFIG. 4, a pedestrian 70 and a preceding vehicle 80 belong within thecollision prediction area S, an object position P3 pertaining topedestrians 70 and an object position P4 pertaining to the precedingvehicle 80 are acquired by the preliminary determination unit 13, andthe object information pertaining to the object positions P3 and P4 isinput in the target selection unit 14. Note that, in this case, theidentification determination unit 141 determines that the objectpositions P3 and P4 are not on the same object.

When the identification determination unit 141 determined that theplurality of object positions are not on the same object in a state inwhich a plurality of object positions was acquired, the selection unit142 selects the target position Tt based on an ETTC calculated by afirst calculation unit 144. Specifically, the object position in whichthe ETTC is smaller among the plurality of object positions is selectedas the current target position Tt.

Furthermore, when each ETTC of the plurality of object positions areequal to each other, the selection unit 142 selects the target positionTt based on the TTC calculated by a second calculation unit 145.Specifically, the object position in which the TTC is smaller among theplurality of object positions is selected as the current target positionTt.

The first calculation unit 144 calculates the ETTC (Enhanced TTC) as thefirst TTC. The ETTC is a value obtained by taking the relativeacceleration A between the own vehicle 50 and the object position intoaccount, and is calculated using a motion equation for uniform linearmotion, for example, as shown in the following formula (1).

ETTC=−V±√(V2−2AD)/A  (1)

Further, the second calculation unit 145 calculates the TTC as thesecond TTC. The TTC is a value obtained by dividing the relativedistance D in the traveling direction (Y axis) between the own vehicle50 and the object position by the relative speed V between the ownvehicle 50 and the object position, and is calculated using a motionequation for the uniform linear motion, for example, as shown in thefollowing formula (2).

TTC=−D/V  (2)

Therefore, the ETTC is calculated using the relative acceleration A,whereas the TTC is calculated without using the relative acceleration A.Note that, the relative speed V is a negative value when the own vehicle50 is approaching the object, and is a positive value when the ownvehicle 50 is moving away from the object. Further, the ETTC becomes animaginary number when the expression V2−2AD inside the square rootsymbol √ in formula (1) is a negative value. This case shows the statein which the own vehicle 50 is moving away from the object, and showsthat there is no possibility of a collision.

Considering the relative acceleration A in the scene in FIG. 4, forexample, a preceding vehicle 80 accelerates and moves away from the ownvehicle 50, whereas when a pedestrian 70 slows and approaches the ownvehicle 50, if the ETTC pertaining to the object position P4 becomes animaginary number, the object position P3 is selected as the currenttarget position Tt based on the ETTC. In this case, with regards to theTTC, there is the possibility that the TTC pertaining to the objectposition P4 will become smaller than the TTC pertaining to the objectposition P3. Therefore, in the conventional vehicle control device whichselects the target position Tt based on the TTC, the object position P3can become the target position Tt, but the target position Tt can beselected taking sudden acceleration and deceleration into account bypreferentially using the ETTC which considered the relative accelerationA.

The process for selecting the target position Tt performed in the targetselection unit 14 of the ECU 10 will be explained using the flowchart ofFIG. 5. The process of selecting the target position Tt is repeatedlyperformed at a predetermined period.

In Step S11, the object position acquired by the preliminarydetermination unit 13 is input. In Step S12, it is determined whether ornot the input object position is a plurality (two or more). When thedetermination at Step S12 was No, in short, when there is one objectposition input from the preliminary determination unit 13, the targetposition Tt is selected as the object position (Step S25).

When the determination at Step S12 was Yes, in short, when a pluralityof object positions input from the preliminary determination unit 13 arepresent, the process proceeds to Step S13, and two targets (objectpositions) are arbitrarily extracted from among the plurality of objectpositions. Note that, the extraction of the object position in Step S13is not specifically limited, for example, the object position may beextracted in ascending order of the number of object positions.

In Step S14, it is determined whether or not the two object positionswhich were extracted in Step S13 are present on the same object. It isdetermined whether or not the relative distance, the relative speed, andthe horizontal position of one object are close to the relativedistance, the relative speed, and the horizontal position of the otherobject respectively. For example, when the difference of the relativedistance between the two object positions is 50 cm or less, thedifference of the relative speeds is 2 km/h or less, and the differenceof the horizontal positions is 1 m or less, it is determined that thetwo object positions are present on the same object. In the case whenStep S14 was affirmed, the process proceeds to Step S15.

Moreover, Steps S15 to S18 are processes for selecting the targetposition Tt from among the two object positions present on the sameobject. Namely, Step S15 determines whether or not the object positionwhich was set as the previous target position Tt is present, Step S16determines whether or not one object position is the fusion position FT,Step S17 determines whether or not the ETTC is different, and Step S18determines whether or not the TTC is different among the two objectpositions. Namely, in the present embodiment, when the plurality ofobject positions has been acquired on the same object, the targetposition Tt is selected in the order of (1) the object position whichwas set as the previous target position Tt, (2) the fusion position FT,(3) the object position in which the ETTC is small, and (4) the objectposition in which the TTC is small.

Moreover, if Step S15 was YES, the object position which was set as theprevious target position Tt is selected as a candidate target (StepS19), and if Step S15 was NO and Step S16 was YES, the fusion positionFT is selected as the candidate target (Step S20). Further, when StepS16 was NO, in short, when both of the two object positions are thefusion position FT or both of the two object positions are not thefusion position FT, the process proceeds to Step S17. Moreover, if StepS17 was YES, the object position in which the ETTC is smaller isselected as the candidate target (Step S21), and if Step S17 was NO andStep S18 was YES, the object position in which the TTC is smaller isselected as the candidate target (Step S22).

On the one hand, if Step S18 was NO, the candidate target having asmaller number of object positions is selected (Step S23). Note that,the present embodiment is constituted so that the number of objectpositions is assigned in a sequentially ascending order of the detectedobject positions. In short, in Step S23, the previously detected objectpositions are selected in chronological order as the candidate targets.

On the one hand, when Step S14 was denied, in short, when it wasdetermined that the two object positions extracted in Step S13 are notpresent on the same object, it is assumed that there actually are aplurality of objects present, and the process proceeds to Step S17. Insuch cases, the target position Tt is selected in the order of (1) theobject position in which the ETTC is smaller and (2) the object positionin which the TTC is smaller.

As stated above, in Steps S19 to S23, if the object position which isthe candidate target is selected from among two object positionsextracted in Step S13, the process proceeds to Step S24. In Step S24, itis determined whether or not object positions other than the two objectpositions extracted in Step S13 are not present. In the case when thedetermination at Step S24 was Yes, in short, when the other objectpositions are not present, the process proceeds to Step S25, and thecandidate target is selected as the target position Tt.

On the one hand, when Step S24 was denied, in short, when another objectposition is present, the candidate targets are maintained and the objectposition which is not the candidate target is changed (Step S31), andthe process proceeds to Step S14. Moreover, in Step S14, it isdetermined whether or not the two object positions which are newcombination are present on the same object, and the process proceeds tothe following step. In short, Step S24 is affirmed, and the processes ofSteps S14 to S23 are repeated until the candidate targets are narroweddown to one. Moreover, the object position finally selected as thecandidate target is selected as the target position Tt (Step S25).

The following excellent result can be obtained by the present embodimentdescribed in detail above.

In the aforementioned configuration, when the plurality of objectpositions was acquired, it is determined that the plurality of objectpositions is on the same object, and in the case when it was determinedthat the plurality of object positions is on the same object, thecurrent target position Tt is selected from among the plurality ofobject positions based on the previous object position which was set asthe target position Tt. In this case, by selecting the current targetposition Tt based on the previous object position which was set as thetarget position Tt, the current target position Tt can be selected whiletaking the fact that the target position Tt is switched into account.Therefore, even when a plurality of object positions are acquired on thesame object, the object position to be the target position Tt can bestably selected, and thus, the safety device can be properly operated.

Specifically, when the object position which was set as the previoustarget position Tt is present in the plurality of object positions in astate in which a plurality of object positions are present on the sameobject, the previous target position Tt is selected as the currenttarget position Tt, thus, the current target position Tt is not changedfrom the previous target position Tt. Therefore, the safety device canbe stably operated.

On the one hand, when the object position which was set as the previoustarget position Tt is not present in the plurality of object positionsin a state in which a plurality of object positions are acquired on thesame object, the fusion position FT is selected as the current targetposition Tt, thus, the object position having a high position accuracycan be selected as the current target position Tt. Further, for example,when a plurality of object positions are acquired on the object which isdetected for the first time, the fusion position FT is selected fromamong the plurality of object positions as the current target positionTt, and in this case, once the fusion position FT is selected, as longas the plurality of object positions are thereafter acquired on theobject, the fusion position FT is continuously selected as the targetposition Tt, thus, the safety device can be properly operated.

In the aforementioned configuration, when a plurality of objectpositions in front of the own vehicle 50 are acquired, and, the objectposition which was set as the previous target position Tt is present inthe plurality of object positions, the object position is preferentiallyselected as the current target position Tt when it was determined thatthese object positions are on the same object, and the object positionin which the ETTC is smaller is selected as the current target positionTt. when it was determined that the plurality of object positions arenot on the same object, In this case, the aspects of the selection ofthe target position Tt were different in accordance with the pluralityof object positions present on the same object, or present on objectswhich are different from each other, thus, depending on the state,indices suitable for the selection of the target position Tt can be usedpreferentially, and the target position Tt can be appropriately selectedin accordance with each state.

In this case, when the plurality of object positions is on objects whichare different from each other, the target position Tt is selected basedon the ETTC in consideration of the relative acceleration A, thus, bytaking the sudden acceleration and deceleration of the object intoaccount, the object position which is set as the target position Tt canbe selected.

Furthermore, when it is determined that the plurality of objectpositions are not on the same object, and, the first TTC of theplurality of object positions is equal, the object position in which thesecond TTC is smaller was selected as the current target position Tt,thus, even when the target position Tt cannot be selected based on thefirst TTC, the object position in which the possibility of a collisionis high can be preferably selected by selecting the target position Ttbased on the second TTC.

Further, when a plurality of object positions on the same object areacquired, it is considered that the positions of these objects areapproximately equal to each other in terms of the relative distancebetween each object position and the own vehicle, the relative speedbetween each object position and the own vehicle, and the horizontalposition between each object position and the own vehicle. Inconsideration thereof, when all of the difference between the relativedistance in one object position and the relative distance in the otherobject position is within a predetermined range, the difference betweenthe relative speed in one object position and the relative speed in theother object position is within a predetermined range, and thedifference between the horizontal position in one object position andthe horizontal position in the other object position is within apredetermined range are satisfied, it is determined that the pluralityof object positions is on the same object, thus, it can be accuratelydetermined that the plurality of object positions is on the same object.

OTHER EMBODIMENTS

The aforementioned embodiment is constituted to select the previoustarget position Tt as the current target position Tt when the objectposition which was set as the previous target position Tt is presentamong the plurality of object positions, in a state in which a pluralityof object positions was acquired on the same object, but thisconfiguration may be changed. For example, the object position selectedas the target position Tt a predetermined number of times or more in thepast among the plurality of object positions may be selected as thecurrent target position Tt, and, the object position continuouslyselected as the target position Tt a predetermined number of times ormore in the past among the plurality of object positions may be selectedas the current target position Tt. Note that, the predetermined numberof times is a value of two or more.

In the aforementioned embodiment, the reliability calculation unit 143was constituted to calculate the reliability based on the presence offusion, but it is not limited thereto. For example, the reliabilitycalculation unit 143 may be constituted to calculate the reliabilitybased on a continuously detected continuous detection time. In this kindof configuration, the longer the continuous detection time, the higherthe reliability calculated. Further, the acquired object position may beconstituted to be calculated so that the reliability is differentbetween the radar position LT and the image position CT.

In the aforementioned embodiment, the ECU 10 was applied to a vehicleequipped with the radar device 21 and the imaging device 22 as theobject detection sensors, but this configuration may be changed, and theECU 10 may be applied to a vehicle equipped with only the radar device21 as the object detection sensor, or a vehicle equipped with only theimaging device 22 as the object detection sensor. Note that, in suchcases, the reliability calculation unit 143 may use the abovementionedcontinuous detection time and the like to calculate the reliability.

What is claimed is:
 1. A vehicle control device that detects a positionof an object present in front of a traveling direction of an own vehicleusing an object detection sensor, and operates a safety device foravoiding a collision of the own vehicle with the object or formitigating collision damage based on a detection result, the vehiclecontrol device comprising: an acquisition unit that acquires an objectposition detected by the object detection sensor; an identificationdetermination unit that determines, when a plurality of object positionsis acquired by the acquisition unit, the plurality of object positionsis on the same object; a selection unit that selects a current targetposition as a target of the safety device to operate, from among theplurality of object positions on the same object determined by theidentification determination unit, based on a previous object positionset as a previous target position that was a target of the safety deviceto operate; and an operation control unit that controls operation of thesafety device based on the current target position.
 2. The vehiclecontrol device according to claim 1, wherein, in the case where theidentification determination unit determines that the plurality ofobject positions is on the same object and when an object position thatwas set as the previous target position is present among the pluralityof object positions, the selection unit preferentially selects theobject position set as the previous target position to be the currenttarget position.
 3. The vehicle control device according to claim 2,wherein vehicle control device includes a reliability calculation unitthat calculates a reliability relating to position accuracy for eachobject position in the case where the identification determination unitdetermines that the plurality of object positions is on the same object,wherein the selection unit selects the object position in which thereliability is in a predetermined range or more as the current targetposition when the object position that was set as the previous targetposition is not present in the plurality of object positions.
 4. Thevehicle control device according to claim 1, wherein the vehicle controldevice includes a calculation unit that respectively calculates, in eachacquired object position, a time to collision as TTC defined as a timeuntil the own vehicle collides with the object positions based on adistance between the own vehicle and the object position, a relativespeed, and a relative acceleration, wherein the selection unitdetermines that the plurality of object positions identified by theidentification determination unit is on the same object, in a statewhere a plurality of object positions in front of the travelingdirection of the own vehicle were acquired, and, preferentially selectsthe object position as the current target position, when the objectposition that was set as the previous target position is present amongthe plurality of object positions, and selects the object position inwhich the TTC is smaller as the current target position when theidentification determination unit determined that the plurality ofobject positions are not on the same object.
 5. The vehicle controldevice according to claim 4, wherein the calculation unit is configuredas a first calculation unit that calculates a first TTC as the TTC, anda second calculation unit that respectively calculates a second TTC thatis the time until the own vehicle collides with the object positionbased on the distance between the own vehicle and the object positionand the relative speed in each acquired object position, wherein theselection unit determines that the plurality of object positionsidentified by the identification determination unit are not on the sameobject, in a state in which a plurality of object positions in front ofthe traveling direction of the own vehicle were acquired, and, selectsthe object position in which the second TTC is smaller as the currenttarget position when the first TTC of the plurality of object positionsis equal.
 6. The vehicle control device according to claim 1, whereinthe identification determination unit determines that the plurality ofobject positions is on the same object based on the distance between theown vehicle from each object position acquired by the acquisition unit,the relative speed, and a horizontal position in a direction orthogonalto the traveling direction of the own vehicle.